Bug#977203: IM_MODULE env for fcitx5 should be "fcitx"

[Gunnar Hjalmarsson <gunnarhj@debian.org>]

If both fcitx 4 and fcitx 5 are installed, the IM_MODULE value "fcitx" 
would result in a fcitx 4 im module being loaded when using fcitx 5. We 
have so far assumed that that would be a problem, if I understand it 
correctly, and that's the reason why the fix of this bug was postponed.

Question: How would it be a problem?

I'm asking since we have an ongoing discussion at Ubuntu about fcitx 5 
and snaps. [1] A snap is an application package in a confined 
environment, and at this time only fcitx 4 im modules are installed in 
that environment. The situation seems similar to the issue with some 
proprietary Qt software as described at 
<https://wiki.debian.org/I18n/Fcitx5#Known_Issues>.

I tested to use fcitx 5 on a gtk based snap (Chromium as snap), and it 
failed with the default configuration, but worked fine when setting 
GTK_IM_MODULE=fcitx. Well, "worked" with a caveat: Me being able to 
input "北京" in the search field may not be the most comprehensive test 
you can imagine.

But can it be that it was a mistake to postpone the fix of this bug? Are 
there any significant adverse side effects if using fcitx 5 but loading 
a fcitx 4 im module? Has anybody really tried to find out?

[1] https://launchpad.net/bugs/1928360, starting with comment #19

--
Rgds,
Gunnar